Shoe molded by induction heating

ABSTRACT

The invention concerns a shoe whose bottom has a layer of thermoplastic material in it and which has embodied in its bottom electromagnetic energy-absorbing material which can be heated by alternating magnetic flux, thus activating the layer of thermoplastic material which then can be molded according to the contour of a human foot.

United States Patent; 11 1 Von Den Benken 1451 July 29,1975

SHOE MOLDED BY INDUCTION HEATING lnventor: Elisabeth Von Den Benken, 2212 Centre St., West Roxbury, Mass.

Filed: Mar. 29, 1973 Appl. No.: 346,428

Related US. Application Data Continuation of Ser. No. 146,312, May 24, 1971, which is a division of Ser; No. 883,952, Dec. 10, 1969, Pat. No. 3,641,688.

US. Cl 12/142 R Int. Cl A43d 9/00 Field of Search 36/25 R, 2.5 AL, 43;

[56] References Cited UNITED STATES PATENTS 3,221,353 12/1965 ,Greene l2/l42 R 3,493,986 2/1970 Erwin 12/142 R 3,521,385 7/1970 Dalebout 36/2.5 AL

Prim'ary Examiner-Patrick D. Lawson [57] ABSTRACT The invention concerns a'shoe whose bottom has a layer of thermoplastic material in it and which has embodied in its bottom electromagnetic energyabsorbing material which can be heated by alternating magnetic flux, thus activating the layer of thermoplastic material which then can be molded according to the contour of a human foot.

2 Claims, '3 Drawing Figures 1 SHOE MOLDED BY INDUCTION HEATING BACKGROUND OF THE INVENTION This is a continuing application of divisional application Ser. No.: 146,312, filed May 24, 1971; said 'divisional application is a division of application Ser. No.: 883,952, filed, Dec. 10,1969; now US. Pat. No.:

This invention relates to footwear of any kind, as boots, sandals, shoes, etc... However, henceforth the word shoe will be used only. Human feet vary in length,

width and contour. There is even a difference between theleft and the right foot of the same person, due to gait and walking habits. In a shoe factory, the shoes are made over lasts which are to represent human feet. These lasts take into consideration the various lengths and widths, but as to the contour of a foot, they are a compromise only.

In the past, when shoes were hand-made and leather was the only material used, they could be fitted to the overall contour of each individual foot. Moreover, a leather shoe has the outstanding feature of gradually shaping itself to the contour of a human foot. The advantages of hand-made leather shoes have been lost to a great extent in present-day mass production. In particular, leather is replaced by synthetic material which .does not possess the feature of shaping itself to the contour of a human foot. For this reason, it is hard to break in new shoes made of synthetic material.

SUMMARY OF THE INVENTION It is the main objective of this invention to provide a finished shoe whose bottom can be quickly molded according to the bottom contour of a human foot at any time after the shoe has left the factory. This does not only eliminate the long break-in time and the disadvan- DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 is shown a cement lasted shoe. However, it should be understood that this invention is applicable to any kind of shoe construction. The insole 8 is made of thermoplastic material, for instance thermoplastic foam made of polyethylene, polypropylene, polyvinyl chloride, etc. Adjacent to the insole 8 are located electromagnetic energy-absorbing discs 4 which are shown somewhat enlarged for the sake of illustration. The electromagnetic energy-absorbing discs can be made of any conducting material such as steel, copper, aluminum, graphite, etc Also, the shape of the material 4 is functionally unimportant. Furthermore, the location of the electromagnetic energy-absorbing material 4 in the bottom of the shoe might vary with each type of shoe. For instance, it could very well be part of the filler material 6. In some cases it might be attached to the outsole 6. The upper 10 and its lining' 12 are made of a material which can withstand the activation temperature of the thermoplastic insole 8.

In FIG. 2 is shown a thermoplastic insole 8 which has been activated and molded according to the contours of the toes of the foot F.

In FIG. 3, the foot F with shoe rests on the coils 14 of an induction heating machine. In this illustration, the thermoplastic insole 8 is shown prior to activation and molding. Shoes which have been made with electromagnetic energy-absorbing material 4 located in an appropriate bottom area according to the construction of v the shoe, are shipped to a retail store as usual.

tages of mass-produced shoes, but also can be of particular importance for people who have crippled or ab- ,normal feet.

I able, and they will be referred to in conjunction with this invention only. When the thermoplastic material is "activated, and a person lets the weight of his body rest on the bottom of the shoe, the imprint of the foot will be in the shoe in less than a minute.

DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example, with reference to the drawings.

FIG. 1 is a perspective view of a shoe with a transverse section through the forepart area.

FIG. 2 is a transverse section of a shoe showing the insole contoured according to the toes of a foot.

FIG. 3 is a perspective view of a shoe with a foot in A retail store has to be equipped with an induction heating machine (not shown in the drawing). After a customer has selected a pair of shoes she puts them on and stands on the coils 14 of an induction heating machine. When the induction heating machine is turned on, an alternating electromagnetic field surrounds the coils l4 and transfers part of its energy to the electromagnetic energy-absorbing material 4. In the material 4 the electromagnetic energy is changed into heat. Then, this heat activates the thermoplastic insole 8 or a similar layer of plastic material in the bottom of the shoe. Under the weight of the body, the activated thermoplastic insole 8 will mold according to the contour of the bottom of the customers foot. Of course, the activation temperature of the thermoplastic material is such that the foot does not suffer from burns. Also, the

frequencies of an induction heating machine are not in any way dangerous to human health.

The construction of the shoe, the kind of thermoplastic material, and the shape and kind of electromagnetic energy-absorbing material will necessitate various embodiments without departing from the character of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the i United States is:

l. A method of shaping the bottom of a shoe according to the contour of afoot, which comprises:

7 itand a cut-away view of the bottom area. The shoe is resting on coils of an induction heating machine.

joining a layer of thermoplastic material with an elec- ,tromagnetic energy absorbing material;

placing the layer of thermoplastic material in the bottom area of a shoe; exposing the shoe to an alter nating electromagnetic field of an induction heating machine thereby heating the layer of thermoplastic material to a temperature at which said layer becomes soft and moldable;

stepping into the shoe and pressing the foot on the bottom of the shoe thereby making an imprint of the foot in the bottom of the shoe; and

cooling thelayer of thermoplastic material thereby hardening said layer and maintaining the imprint in it.

2. A method of shaping the bottom of a shoe according to the contour of a foot; which comprises:

embedding electromagnetic energy absorbing particles in a layer of thermoplastic material; I

making the shoe in a shoe factory with said layer of thermoplastic material firmly and integrally lobottom of the shoe thereby, making an imprint of the foot in the bottom of the shoe; and cooling the layer of thermoplastic material therebyhardening said layer and maintaining the imprint in it. 

1. A method of shaping the bottom of a shoe according to the contour of a foot, which comprises: joining a layer of thermoplastic material with an electromagnetic energy absorbing material; placing the layer of thermoplastic material in the bottom area of a shoe; exposing the shoe to an alternating electromagnetic field of an induction heating machine thereby heating the layer of thermoplastic material to a temperature at which said layer becomes soft and moldable; stepping into the shoe and pressing the foot on the bottom of the shoe thereby making an imprint of the foot in the bottom of the shoe; and cooling the layer of thermoplastic material thereby hardening said layer and maintaining the imprint in it.
 2. A method of shaping the bottom of a shoe according to the contour of a foot; which comprises: embedding electromagnetic energy absorbing particles in a layer of thermoplastic material; making the shoe in a shoe factory with said layer of thermoplastic material firmly and integrally located in the bottom area of the shoe; transporting the shoe to a locality where a customer can select the shoe according to his foot size and taste; heatiNg the layer of thermoplastic material in the shoe by induction heating to a temperature at which said layer becomes soft and moldable; stepping into the shoe and pressing the foot on the bottom of the shoe thereby making an imprint of the foot in the bottom of the shoe; and cooling the layer of thermoplastic material thereby hardening said layer and maintaining the imprint in it. 